Microbial corrosion of galvanized steel in a simulated recirculating cooling tower system

In this study, mixed species biofilm formation including sulphate reducing bacteria (SRB) on the galvanized steel surfaces and also microbiologically influenced corrosion (MIC) of galvanized steel were observed in a model recirculating cooling water system during 10 months. A biofilm which had a heterogeneous structure formed on galvanized steel coupons. The results suggested that galvanized steel was corroded by microorganisms as well as SRB in the biofilm. Extracellular carbohydrate was degraded and quantities of carbohydrate were positively correlated with the weight loss. The concentrations of zinc in the biofilm showed significant correlations with weight loss, carbohydrate amount and SRB count.